The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque that propels the vehicle. Airflow into the engine is regulated using a throttle. When a driver depresses an accelerator pedal, the throttle is commanded to open and allows air into the engine.
More specifically, the throttle adjusts a throttle area. As the throttle area increases, the airflow entering the engine increases. The throttle position is monitored by a throttle position sensor (TPS). A mass airflow (MAF) sensor monitors the amount of air entering the engine. An oxygen (O2) sensor monitors the air-fuel ratio of the engine exhaust. An engine coolant temperature (ECT) sensor monitors the engine coolant temperature. Based on signals from the TPS, the MAF sensor, the O2 sensor, and the ECT sensor, an engine control module controls the fuel injection system to achieve a desired amount of fuel to mix with the air entering each cylinder.
A fuel system typically includes a fuel tank, a fuel pump, a fuel rail, and fuel injectors. The fuel pump delivers fuel from the fuel tank to the fuel rail through a fuel line. An inlet portion of each of the fuel injectors receives fuel from the fuel rail and an outlet portion of each of the fuel injectors is connected to the engine.
The fuel injectors may inject fuel into an intake manifold at a central location or may inject fuel into the intake manifold at multiple locations, such as near the intake valve of each of the cylinders. Alternatively, the fuel injectors may inject fuel directly into the cylinders, referred to as direct injection. The injected fuel mixes with the air and creates the air-fuel mixture in the cylinders.
In a spark ignited (also referred to as spark ignition) engine, the air-fuel mixture combusts when a spark plug is energized. A spark actuator module enables the spark plug to be energized, which ignites the air-fuel mixture. The timing of the spark may be specified relative to the time when a piston in the cylinder is at its topmost position, referred to as top dead center (TDC), the point at which the air-fuel mixture is most compressed. The combustion of the air-fuel mixture drives the piston down, thereby driving a rotating crankshaft.